fix(newos4): world_model_query default path parses again (v4.6.83-84)

_modelDigest() returned JSON.stringify(...) cut at 4000 chars plus '…(digest truncated)'. The
tool then did JSON.parse() on it, so the default detail threw 'Unexpected end of JSON input'
every single call; detail:'full' worked only because it returned the object untouched.

The digest now returns an OBJECT (_modelSnapshot) and shrinks by reducing list lengths, then by
dropping whole sections with an explicit 'omitted' list. The string form is generated at the
edge and is always valid JSON.

Verified: default call -> no error, 13-key snapshot, facts answered; caps 400/1200/4000 all under
cap and parseable; the residual floor at cap 200 is identity fields only.

6 files changed, 93 insertions, 24 deletions

diff --git a/help.html b/help.html
index acffae6..5bf3543 100644
--- a/help.html
+++ b/help.html
@@ -1689,6 +1689,23 @@ listmods</pre>
     <h2>📋 Changelog</h2>
 
     <div class="version-item">
+      <div class="v-header"><span class="v-num">v4.6.83–84 — October 2026</span>
+        <span class="v-date">world_model_query</span></div>
+      <ul>
+        <li><strong>The first tool the system prompt tells the model to call no longer fails.</strong>
+          <code>world_model_query</code> with the default detail parsed
+          <code>_modelDigest()</code> as JSON — but that digest was a JSON <em>string</em> cut at 4000
+          characters with <code>…(digest truncated)</code> glued on, so it threw
+          <code>Unexpected end of JSON input</code> every time. <code>detail:"full"</code> worked only
+          because it returned the object and never parsed anything.</li>
+        <li><strong>A digest shrinks, it does not break.</strong> The model now builds a real
+          snapshot object and drops list lengths (40 → 20 → 10 → 5 → 3 → 1 → 0), and if still too
+          large drops whole sections, reporting what it left out in <code>omitted</code>. The string
+          form is only produced at the edge, and is always parseable.</li>
+      </ul>
+    </div>
+
+    <div class="version-item">
       <div class="v-header"><span class="v-num">v4.6.82 — October 2026</span>
         <span class="v-date">skill-create parser</span></div>
       <ul>
diff --git a/main.html b/main.html
index 81a87b3..41a7c82 100644
--- a/main.html
+++ b/main.html
@@ -1349,13 +1349,13 @@
     </script>
 
     <!-- v4.5.63: A2A scratchpad fixes + agent-register arg fix -->
-<script src="modules/core/core-bundle.js?v=v4.6.82"></script>
+<script src="modules/core/core-bundle.js?v=v4.6.84"></script>
 
     <!-- Async dependency-ordered module loader now only initializes terminal and loads optional ext modules -->
-<script src="modules/core/module-loader.js?v=v4.6.82"></script>
+<script src="modules/core/module-loader.js?v=v4.6.84"></script>
 
     <!-- Critical ext bundle loads AFTER webx11 exists so registerModule calls work -->
-<script src="modules/ext/critical-ext-bundle.js?v=v4.6.82"></script>
+<script src="modules/ext/critical-ext-bundle.js?v=v4.6.84"></script>
 
 <script>
 // ═══ ONE TRUE VERSION SOURCE ═══
diff --git a/modules/core/core-bundle.js b/modules/core/core-bundle.js
index b565365..0b2795a 100644
--- a/modules/core/core-bundle.js
+++ b/modules/core/core-bundle.js
@@ -11557,7 +11557,10 @@ buildSystemPrompt() {
                                 facts: wm._answerQuery(a.question || ''),
                                 version: wm._model.version,
                                 synthesized: wm._model.synthesized,
-                                snapshot: (a.detail === 'full') ? wm._model : JSON.parse(wm._modelDigest())
+                                // v4.6.83: this was JSON.parse(wm._modelDigest()) and the digest was a
+                                // string truncated mid-token, so the default path always threw
+                                // "Unexpected end of JSON input". The model now hands back an object.
+                                snapshot: (a.detail === 'full') ? wm._model : wm._modelSnapshot()
                             };
                             return JSON.stringify(wmOut);
                         }
@@ -19051,30 +19054,53 @@ class WorldModelModule {
     // 2026-10-21: ask() used to be a keyword table only, so any real question got
     // "Unknown query". Whitelist the fields we are willing to send to a model
     // (never the raw model object: it is persisted alongside other VFS data).
-    _modelDigest(maxChars) {
+    // v4.6.83: the digest used to be a JSON string cut at 4000 chars with '…(digest truncated)'
+    // glued on. Every caller that tried to parse it got "Unexpected end of JSON input" — the
+    // world_model_query tool did exactly that on its default path. A digest must shrink, never
+    // break: this returns a valid OBJECT and the string form is only produced at the edge.
+    _modelSnapshot(maxChars) {
         const m = this._model;
-        if (!m) return '';
+        if (!m) return null;
         const cap = maxChars || 4000;
-        const pick = {
+        const build = (keep) => ({
             version: m.version,
             synthesized: m.synthesized,
             system: m.system,
             modules: m.modules,
             files: m.files,
-            skills: { count: m.skills && m.skills.count, skills: ((m.skills && m.skills.skills) || []).slice(0, 40) },
+            skills: { count: m.skills && m.skills.count, skills: ((m.skills && m.skills.skills) || []).slice(0, keep) },
             memory: m.memory,
             agents: m.agents,
             telemetry: m.telemetry,
             projects: m.projects,
-            recent: (m.recent || []).slice(0, 20),
+            recent: (m.recent || []).slice(0, Math.min(keep, 20)),
             // 2026-10-21: the model only ever exposed a COUNT ("9 recent errors") with no detail,
             // so neither the user nor the LLM could say what failed. Carry the last few.
             recentErrorSample: this._errorSample ? this._errorSample() : [],
             changesSinceLastSnapshot: this._diffSincePrev ? this._diffSincePrev() : []
-        };
-        let json = JSON.stringify(pick);
-        if (json.length > cap) json = json.slice(0, cap) + '…(digest truncated)';
-        return json;
+        });
+        // Shrink the lists until the snapshot fits. Truncating the JSON text is what broke it.
+        for (const keep of [40, 20, 10, 5, 3, 1, 0]) {
+            const pick = build(keep);
+            if (JSON.stringify(pick).length <= cap) return pick;
+        }
+        // Last resort: drop whole sections, in order of least value, until it fits. Still a
+        // valid object — a caller can always JSON.parse it and see what was left out.
+        const lean = build(0);
+        lean.truncated = true;
+        lean.omitted = [];
+        for (const key of ['changesSinceLastSnapshot', 'recentErrorSample', 'recent', 'projects',
+                           'skills', 'agents', 'files', 'modules', 'telemetry', 'memory']) {
+            if (JSON.stringify(lean).length <= cap) break;
+            if (key in lean) { delete lean[key]; lean.omitted.push(key); }
+        }
+        return lean;
+    }
+
+    // String form, for prompts. Always valid JSON now.
+    _modelDigest(maxChars) {
+        const snap = this._modelSnapshot(maxChars);
+        return snap ? JSON.stringify(snap) : '';
     }
 
     // Last few tool/agent errors with their tool name, for the digest (bounded).
diff --git a/modules/core/module-aiassist.js b/modules/core/module-aiassist.js
index c3ebe1f..55dde6f 100644
--- a/modules/core/module-aiassist.js
+++ b/modules/core/module-aiassist.js
@@ -3170,7 +3170,10 @@ buildSystemPrompt() {
                                 facts: wm._answerQuery(a.question || ''),
                                 version: wm._model.version,
                                 synthesized: wm._model.synthesized,
-                                snapshot: (a.detail === 'full') ? wm._model : JSON.parse(wm._modelDigest())
+                                // v4.6.83: this was JSON.parse(wm._modelDigest()) and the digest was a
+                                // string truncated mid-token, so the default path always threw
+                                // "Unexpected end of JSON input". The model now hands back an object.
+                                snapshot: (a.detail === 'full') ? wm._model : wm._modelSnapshot()
                             };
                             return JSON.stringify(wmOut);
                         }
diff --git a/modules/core/module-loader.js b/modules/core/module-loader.js
index 626d7bc..9a373a6 100644
--- a/modules/core/module-loader.js
+++ b/modules/core/module-loader.js
@@ -4,7 +4,7 @@
     // Core module bundle loaded synchronously in main.html.
     // This loader only handles version cache-busting, splash, terminal init, and optional ext modules.
 
-    const LATEST_VER = 'v4.6.82';
+    const LATEST_VER = 'v4.6.84';
     const CACHE = '?v=' + LATEST_VER;
     const stored = localStorage.getItem('webx11_cache_ver');
     if (stored !== LATEST_VER) {
diff --git a/modules/core/module-world-model.js b/modules/core/module-world-model.js
index d48327b..54a17e4 100644
--- a/modules/core/module-world-model.js
+++ b/modules/core/module-world-model.js
@@ -446,30 +446,53 @@ class WorldModelModule {
     // 2026-10-21: ask() used to be a keyword table only, so any real question got
     // "Unknown query". Whitelist the fields we are willing to send to a model
     // (never the raw model object: it is persisted alongside other VFS data).
-    _modelDigest(maxChars) {
+    // v4.6.83: the digest used to be a JSON string cut at 4000 chars with '…(digest truncated)'
+    // glued on. Every caller that tried to parse it got "Unexpected end of JSON input" — the
+    // world_model_query tool did exactly that on its default path. A digest must shrink, never
+    // break: this returns a valid OBJECT and the string form is only produced at the edge.
+    _modelSnapshot(maxChars) {
         const m = this._model;
-        if (!m) return '';
+        if (!m) return null;
         const cap = maxChars || 4000;
-        const pick = {
+        const build = (keep) => ({
             version: m.version,
             synthesized: m.synthesized,
             system: m.system,
             modules: m.modules,
             files: m.files,
-            skills: { count: m.skills && m.skills.count, skills: ((m.skills && m.skills.skills) || []).slice(0, 40) },
+            skills: { count: m.skills && m.skills.count, skills: ((m.skills && m.skills.skills) || []).slice(0, keep) },
             memory: m.memory,
             agents: m.agents,
             telemetry: m.telemetry,
             projects: m.projects,
-            recent: (m.recent || []).slice(0, 20),
+            recent: (m.recent || []).slice(0, Math.min(keep, 20)),
             // 2026-10-21: the model only ever exposed a COUNT ("9 recent errors") with no detail,
             // so neither the user nor the LLM could say what failed. Carry the last few.
             recentErrorSample: this._errorSample ? this._errorSample() : [],
             changesSinceLastSnapshot: this._diffSincePrev ? this._diffSincePrev() : []
-        };
-        let json = JSON.stringify(pick);
-        if (json.length > cap) json = json.slice(0, cap) + '…(digest truncated)';
-        return json;
+        });
+        // Shrink the lists until the snapshot fits. Truncating the JSON text is what broke it.
+        for (const keep of [40, 20, 10, 5, 3, 1, 0]) {
+            const pick = build(keep);
+            if (JSON.stringify(pick).length <= cap) return pick;
+        }
+        // Last resort: drop whole sections, in order of least value, until it fits. Still a
+        // valid object — a caller can always JSON.parse it and see what was left out.
+        const lean = build(0);
+        lean.truncated = true;
+        lean.omitted = [];
+        for (const key of ['changesSinceLastSnapshot', 'recentErrorSample', 'recent', 'projects',
+                           'skills', 'agents', 'files', 'modules', 'telemetry', 'memory']) {
+            if (JSON.stringify(lean).length <= cap) break;
+            if (key in lean) { delete lean[key]; lean.omitted.push(key); }
+        }
+        return lean;
+    }
+
+    // String form, for prompts. Always valid JSON now.
+    _modelDigest(maxChars) {
+        const snap = this._modelSnapshot(maxChars);
+        return snap ? JSON.stringify(snap) : '';
     }
 
     // Last few tool/agent errors with their tool name, for the digest (bounded).